The present invention relates to the field of container necking apparatus and methods used in the tapered reduction of the diameter of the top portion of beverage and other type of containers. More specifically, the invention relates to a new and improved, simplified and less expensive necking apparatus and method providing enhanced functional results for necking containers such as beverage containers in which only one cam is employed for actuating and driving the tooling to effect the necking function.
A variety of prior art methods and devices have been employed for necking containers. The known prior art devices employ a cylindrical necking die which is reciprocated axially to engage the exterior of the upper end of a container workpiece and a coaxial die pilot, also known as a xe2x80x9cknockoutxe2x80x9d or xe2x80x9cpilot,xe2x80x9d which simultaneously moves axially in a mating manner into the open end of the container workpiece. The aforementioned prior art devices have employed a variety of complicated and expensive drive arrangements including a first cam for driving the necking die and a second cam for driving the pilot die.
While many of the prior devices have provided satisfactory results and have been capable of operating at progressively higher speeds during the recent years, such devices have been increasingly complex in construction and have been extremely expensive to manufacture and maintain.
For example, Lee et al. U.S. Pat. No. 5,249,449 discloses a can necking apparatus of complex construction in which a necking die and a pilot are reciprocated in unison into contact with a can body that is pressured with air. The pilot and the necking die are capable of axial movement relative to each other and forward movement of the pilot is terminated by engagement of flange with a bumper ring as shown on the left end of FIG. 1 of the Lee et al. patent. However, the necking die continues forward movement after forward movement of the pilot has been terminated. Thus, substantial vibration and noise as well as complexity of construction render the device of this patent to be expensive to construct and maintain. The device of the Lee patent is additionally deficient in that it is incapable of operating at high speeds comparable to other conventional necking devices.
Similarly, Miller et al. U.S. Pat. No. 4,457,158 is directed to a can necking apparatus employing a complex mechanically driven structure for effecting container necking by moving a die member and a pilot forwardly into the open end of a container workpiece. The pilot has its forward travel terminated by engagement of its surfaces and with surfaces with of the base of the apparatus. Here again, noise and vibration are substantial problems which limit the speed of operation and reliability of the device.
More recently, Marritt et al. U.S. Pat. No. 6,167,743, the contents of which are hereby incorporated by reference, disclosed an improved necking apparatus having a knockout ram assembly 18 with only a single cam for operating the necking tooling (see FIG. 7). The apparatus uses a floating piston 34 having an axial bore 37. Air supplied to the back of the piston both urges the piston 34 forward and flows through the axial bore 37 to help seat and pressurize the can during necking. Although simpler and more reliable than previous necking apparatus, converting a necking turret to use the knockout ram assembly 18 proved difficult in practice, requiring roughly a full day to accomplish.
Therefore, it would be advantageous to provide a simple, reliable knockout ram assembly which can be easily and more quickly replaced than conventional knockout ram assemblies.
One embodiment of the present invention includes a knockout ram assembly for necking a container comprising an anti-rotation device adapted to prevent a piston/pilot assembly from rotating while bolting or unbolting the knockout ram assembly from a container necking apparatus.
In another embodiment of the invention, the anti-rotation device comprises a hollow cylinder adapted to fit in registration with two flats on a shaft of a pilot.
In another embodiment of the invention, the anti-rotation device includes at least one roll pin.
A further embodiment of the present invention includes a method of replacing a knockout ram assembly from a container necking apparatus comprising unbolting from the container necking apparatus a first knockout ram assembly having an anti-rotation device adapted to substantially prevent the piston/pilot assembly from rotating; removing the first knockout ram assembly from the container necking apparatus; and bolting to the container necking apparatus a second knockout ram assembly having an anti-rotation device adapted to substantially prevent the piston/pilot assembly from rotating.
A further embodiment of the present invention includes a knockout ram assembly for necking a container comprising a floating piston/pilot assembly including a pilot having a front, a back and at least one through hole connecting the front and back and a piston having a front and back, said piston and pilot oriented such that front of the piston faces the back of the pilot; a necking die; a pressurized air input conduit; a first pressurized air delivery conduit configured to deliver pressurized air to the back of the piston; and a second pressurized air delivery conduit configured to supply air through the pilot into the container, wherein pressurized air from the pressurized air input conduit substantially simultaneously forces the floating piston/pilot assembly forward via the first pressurized air delivery conduit and charges the container with pressurized air via the second pressurized air delivery conduit.
In another embodiment of the invention, the container receives sufficient air volume to hold the container rigid during necking.
In another embodiment of the invention, the piston/pilot assembly receives sufficient air pressure to hold said piston/pilot assembly fully forward to maintain pilot interface for neck support while necking the container.
In another embodiment of the invention, the assembly is adapted so that the container seals in the necking die and when the container seals in the necking die, the air flow decreases in the container causing the air pressure in the assembly to equalize.
In another embodiment of the invention, the knockout ram assembly further comprises an adjustable travel delimeter to ensure sufficient neck support is maintained during necking.
In another embodiment of the invention, the knockout ram assembly further comprises an anti-rotation device.
In another embodiment of the invention, the anti-rotation device has a cross section selected from the group consisting of truncated circular, elliptical and hexagonal.
A further embodiment of the invention includes a knockout ram assembly for necking a container comprising: a pilot/piston assembly including a pilot and a piston, wherein the piston and the pilot are adapted such that the piston diameter is essentially equal to the pilot diameter for each stage of necking.
In another embodiment of the invention, the knockout ram assembly further comprises at least one piston sleeve.
In another embodiment of the invention, air pressure in the container can equalize with air pressure on the piston for each stage of necking.
A further embodiment of the invention includes a method of necking a container comprising supplying a container to a necking machine having a knockout ram assembly having, a floating piston/pilot assembly including a pilot having a front, a back and at least one through hole connecting the front and back and a piston having a front and back, said piston and pilot joined such that front of the piston is connected to the back of the pilot, a necking die, a pressurized air input conduit, a first pressurized air delivery conduit configured to deliver pressurized air to the back of the piston, and a second pressurized air delivery conduit configured to supply air through the pilot into the inside of the container; supplying pressurized air from the pressurized air input source substantially simultaneously to the floating piston/pilot assembly via the first pressurized air conduit to force the floating piston/pilot assembly forward and to the container via the second pressurized air delivery conduit to charge the container with pressurized air; forcing the floating piston/pilot assembly forward; and charging the container with pressurized air.
In another embodiment of the invention, the step of supplying pressurized air supplies the container with sufficient air volume to hold the container rigid during necking.
In another embodiment of the invention, the step of supplying pressurized air supplies the piston/pilot assembly with sufficient air pressure to hold said piston/pilot assembly fully forward to maintain pilot interface for neck support while necking the container.
In another embodiment of the invention, the step of forcing the floating piston/pilot assembly forward comprises forming a seal between the container and the necking die.
In another embodiment of the invention, the step of forcing the floating piston/pilot assembly forward further comprises decreasing air flow to the container and equalizing air pressure in the assembly after forming the seal.
In another embodiment of the invention, the method further comprises the step of substantially preventing the piston/pilot assembly from rotating.
A further embodiment of the present invention includes container necking apparatus comprising a knockout ram assembly as disclosed above.